It has been known for a long time to incorporate cellulose ethers into food compositions, particularly into processed food compositions, to improve various properties, such as freeze thaw stability and/or texture or to improve firmness during manufacturing, machine handling or frying. UK Patent Application GB 2 444 020 discloses such food compositions comprising a non-ionic cellulose ether, such as methyl cellulose, hydroxypropyl cellulose, or hydroxypropyl methylcellulose. Methylcellulose and hydroxypropyl methylcellulose have “thermoreversible gelation properties”. Described specifically, when an aqueous solution of methylcellulose or hydroxypropyl methylcellulose is heated, de-hydration of the hydrophobic methoxyl groups localized in the molecule occurs and it turns into a hydrous gel. When the resulting gel is cooled, on the other hand, the hydrophobic methoxyl groups are re-hydrated, whereby the gel returns to the original aqueous solution.
European Patent EP 1 171 471 discloses methylcellulose which is very useful in solid food compositions, such as solid vegetable, meat, and soy patties, due to its enhanced gel strength. The methylcellulose provides improved hardness and cohesion to the solid food compositions, thus providing excellent bite feel to consumers eating the processed food composition. The methylcellulose reaches its full capacity in providing good hardness and cohesion to solid food compositions when it is dissolved in cooled water, e.g. of 5° C. or less, before or after it is blended with other components of the food composition.
However, in some cases the use of cooled water is inconvenient to producers of food compositions. Accordingly, it would be desirable to provide cellulose ethers which provide good hardness and cohesion to solid food compositions even when the cellulose ethers are dissolved in water that has about room temperature.
Hydroxyalkyl methylcelluloses, such as hydroxypropyl methylcellulose, which are also useful in food compositions, are known to have a low storage modulus, compared to methyl cellulose. Hydroxyalkyl methylcelluloses which exhibit a low storage modulus do not form strong gels. High concentrations are needed to form even weak gels (Hague, A; Richardson, R. K.; Morris, E. R., Gidley, M. J and Caswell, D. C in Carbohydrate Polymers 22 (1993) p. 175; and Hague, A. and Morris, E. R. in Carbohydrate Polymers 22 (1993) p. 161).
When hydroxyalkyl methylcelluloses, such as hydroxypropyl methylcelluloses, which exhibit a low storage modulus are included in solid food compositions, their hardness and cohesion is not sufficiently high for some applications.
One object of the present invention is to provide hydroxyalkyl methylcelluloses, particularly hydroxypropyl methylcelluloses, that provide improved hardness and/or cohesion to solid food compositions, as compared to known comparable hydroxyalkyl methylcelluloses, such as hydroxypropyl methylcelluloses.
A preferred object of the present invention is to provide hydroxyalkyl methylcelluloses, particularly hydroxypropyl methylcelluloses that provide good hardness and/or cohesion to solid food compositions even when the hydroxyalkyl methylcelluloses are dissolved in water that has about room temperature.